<!DOCTYPE html>
<html lang="cn">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>en</title>
</head>

<body>
    <script>
        // 给全局开启严格模式
        'use strict'
        message = '123'
        console.log(message);
        function foo(){
            // 给函数开启严格模式
            'use strict'
        }
    </script>
</body>

</html>